THE DEVONIAN FOSSILS OF CANADA WEST. 281 
that the valve has the appearance of a flat space along the middle. 
The groove on the ridge of the dorsal valve either extends to the 
front margin of the shell, or dies out at a greater or less distance from 
the beak. 
The length of the shell ranges. from two to nine lines, and is 
always a little less than the width. 
Locality and formation.—County of Haldimand. Corniferous 
Limestone. Not common. 
Collectors.—J. De Cew, E. De Cew, and E. Billings. 
Atuyris (?) rostrata.—(Hall.) 
ATRYPA ROSTRATA.—Hall. Geology of the Fourth District of New 
Fork, page 202, fig. 2. 
Fig. 48. Fig, 44, 
Figs. 43, 44. Athyris rostrata.—Dorsal and side views. 
Description.—Elongate oval, both valves evenly convex and smooth, 
Ventral valve the larger, most ventricose in the upper half; beak 
proportionally large, sub-cylindrical, incurved, not in contact with 
the umbo of dorsal valve, apparently perforated by a large foramen. 
Dorsal valve smaller than the ventral, but proportionally as strongly 
convex, umbo rather broadly rounded, beak incurved and deeply. 
buried beneath that of the ventral valve. 
Length about six lines; greatest width a little in front of the mid-. 
dle of the ventral valve, five lines ; depth of both valves a little above 
the middle, three lines and a half. 
The surface at first sight appears to be quite smooth, but upon a 
closer examination it will be found to exhibit some fine obscure con- 
centric rings of growth. 
This neat little fossil is smaller and proportionally broader, and 
more ventricose than A. seitula. 
Locality and formation.—Lot 26, con. 3, Bosanquet. Hamilton 
Shales. 
_Collectors.—A. Murray and J. Richardson. 
Vou. V. WwW 
